The present invention relates to a method and a device for producing a security element for electronically securing objects, as well as a corresponding security element.
The security element is a so-called strip elementxe2x80x94i.e. a low-retentivity magnetic metal strip, or a metal strip having a large Barkhausen effectxe2x80x94which, when an external magnetic alternating field is applied in a monitoring zone, is excited to emit a characteristic signal. The strip element has a sheath whose melting temperature lies below that of the melting temperature of the metal strip. In the same way, the security element can also be a so-called thin film security element, a resonance frequency security element or an accusto-magnetic security element.
Strip elements with plastic sheathing are already known and are used, inter alia, for the electronic securing of an object in the form of seed packaged in seed packages. In connection with this so-called source security, the strip elements are filled into the seed packages together with the seed.
For producing the security elements, a low-retentivity magnetic strip material or a strip material having a large Barkhausen effect is coated on both sides with a plastic foil and is subsequently divided into strip elements of the desired length. It is disadvantageous in connection with the known method, or respectively the security elements produced by means of the method, that the metal is exposed in the end areas and comes into contact with the goods to be secured. The use of the known security elements is not possible in many cases for reasons of customer protection.
The object of the present invention is to provide a method and a device for producing a completely encapsulated security element, as well as a corresponding security element.
Regarding the method, this object is attained by making available a strip element of a preselected length with the sheathing, or any other element for the electronic securing of objects; the sheathing is subsequently heated in the end areas and stretched in the longitudinal direction of the security element until it extends past the end areas of the security element.
In accordance with an advantageous, cost-efficient further development of the method in accordance with the present invention it is provided that a low-retentivity magnetic strip material or a strip material having a large Barkhausen effect, or a strip material which supports other security elements, is made available and is enclosed with a sheathing of plastic in an extrusion process. The strip material with the sheathing is subsequently separated into sections (strip elements) of a defined length.
Regarding the device for producing a security element for electronically securing an object, the object is attained in that the device has two clamping elements, which in a first position (I) clamp the end areas of the sheathed strip element (security element), that a translating mechanism is provided, which makes the clamping elements movable in the longitudinal direction of the clamped security element, that a heating device is provided, which heats at least the end areas of the strip element or other element for the electronic securing of an object, and that following heating of the end elements of the security element, the clamping elements are moved into a further position (II), which at least partially lies outside of the end areas of the strip element or other element for the electronic securing of an object, by means of which the heated and softened end areas of the sheathing are pulled over the ends of the strip element or the other element for the electronic securing of an object.
In accordance with an advantageous further embodiment of the device in accordance with the present invention it is provided that the heating device is integrated in the clamping elements. It has been shown to be particularly advantageous in this connection if the clamping elements are embodied so they can be electrically heated.
In the case of strip elements, an advantageous embodiment of the device of the present invention proposes that a strip, element is in the form of two clamping jaws arranged in a ring shape, which are resiliently seated with respect to each other. If another element for the electronic securing, of an object is encapsulated, the use of two clamping elements, which are arranged parallel with respect to each other, is recommended.
In accordance with a cost-effective embodiment of the device of the present invention it is provided that the control of the temperature of the heating device and/or of the translating mechanism is performed by a control unit.
Regarding the security element itself, the object is attained in that the melting temperature of the sheathing lies below the melting temperature of the strip element, and that the end areas of the sheathing are pulled over the ends of the strip element or the other element for the electronic securing of an object after appropriate heating, so that the strip element or the other element for the electronic securing of an object is completely sealed by the material of the sheathing. Because of the complete encapsulation of the the strip element or the other element for the electronic securing of an object from the goods to be secured, the security element of the present invention can be used without problems for any arbitrary employment.